Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Selection of building materials for a given use depends largely upon the nature of the intended application and in many cases each of the products available represent a compromise between strength characteristics, durability and ease of installation, the latter being largely determined by workability characteristics such as ease of cutting, fixing and handling.
For example, natural timber has good inherent bending strength characteristics making it easy to transport and suitable for use in a variety of load bearing applications. However, it is generally fairly costly and lacks durability, particularly in damp or wet applications.
By contrast, manufactured wood products and fibre cement products, for example, are generally less expensive and more versatile in their application to form different shapes and types of building elements. However, these products generally have relatively lower bending strength to weight ratio due to their inherent weakness under tensile loads. They are also generally porous and prone to some degree of moisture absorption. While in the case of fibre cement products, this does not lead to significant reductions in durability, with most materials there is usually a resultant decrease in the strength characteristics with prolonged and cyclic exposure to moisture. There is also usually a corresponding increase in mass, which may be relevant to the issue of transportation and installation.
The problem of low bending specific strength in building elements made of homogenous bonded materials such as fibre cement has been addressed to some degree by using various forms of added reinforcement. In some cases a reinforcing element is introduced into the main body of the building material during manufacture. However, this has generally required major modifications to the material manufacturing process which can be costly and may inhibit the flexibility of the manufacturing plant.
Other solutions have included the step of externally attaching some form of reinforcing element to the completed base product using fasteners or an adhesive. Examples of this concept as applied to fibre cement building substrates are described in WO 02/081842. However, in conventional production processes, this additional step is generally off line from the normal production line, requires a specific additional fastener/adhesive, is labour intensive and/or time consuming thereby adding substantially to the cost of the product.
It is an object of the invention to provide a reinforced building element, and a method and apparatus for the manufacture of such elements, which overcomes or substantially ameliorates one or more of the disadvantages of the prior art or at least provides a useful alternative.